1. Technical Field
The present invention relates to a technical field of a circuit board used for an electro-optical device such as a liquid crystal device, an electro-optical device having such a circuit board, and an electronic apparatus such as a liquid crystal projector that is provided with such an electro-optical device.
2. Related Art
A Liquid crystal device, which is an example of an electro-optical device, is widely used not only as a direct-view-type display device but also, for example, optical modulation means, such as a light valve, of a projection-type display device. When a liquid crystal device is employed in a projection-type display device, an intense light coming from a light source enters into a liquid crystal light-valve. In order to prevent such an intense light from causing an increase in a leakage current at a thin film transistor (TFT) provided in the liquid crystal light valve and/or any malfunction of the TFT, the liquid crystal light valve has a built-in light-shielding film which functions as light-shutting means for shutting any incident light off. Regarding such light-shielding means or a light-shielding film, as an example of published documents, JP-A-2004-4722 discloses a technique for shutting light off by means of scanning lines each of which functions as a gate electrode in the channel region of a TFT. Japanese Patent No. 3,731,447 discloses a technique in which an amount of light that reaches the channel region of a TFT is reduced by means of a plurality of light-shielding films deposited on the channel region and a light absorption layer that absorbs an inner reflected light JP-A-2003-262888 discloses a technique that makes it possible to ensure the appropriate operation of TFTs and to narrow scanning lines, and further to reduce the amount of an incident light beam that enters the channel region of a TFT as small as possible.
When such a light-shielding film as one described above is used to shut light off to protect a TFT, however, the light-shielding film is deposited not in direct contact with a semiconductor layer that constitutes a part of a TFT but separately therefrom in such a manner that some other layer, for example, an insulator film, is interposed therebetween when viewed in three dimensions. According to such a configuration, there is a risk that an incident light beam entering inside at an oblique angle to bypass the light-shielding film reaches the semiconductor layer that constitutes a part of the TFT thereby causing the generation of a light leakage current in the TFT. Due to the generation of light leakage currents in TFTs as described above, there could occur a technical problem of the generation of a flicker noise, nonuniformity among pixels, and so on, which results in degradation in the quality of a displayed image.